Bioavailability and First Pass Clearance

Question 1

Absorption is

Answer 1

extent to which intact drug is absorbed from gut to portal circulation

Question 2

First pass clearance

Answer 2

extent to which drug removed in first pass through portal system to liver

Question 3

Bioavailability (F)

Answer 3

Fraction of dose that reaches systemic circulation as intact drug

Question 4

Bioavailability formula

Answer 4

F= fraction absorbed x (1-HER)

Question 5

Bioequivalence

Answer 5

two formulations are bioequivalent if extent and rate of absorption is similar resulting in same clinical effect

Question 6

Bioequivalence as AUC ratio must be between

Answer 6

0.8-1.25

Question 7

Bioavailability also equals AUC

Answer 7

AUC oral/AUC IV

AUC test/AUC reference

Question 8

What is impact of low HER on bioavailability?

Answer 8

Not much change as all drug is delivered to liver, F closer to 1

Question 9

High HER drugs impact F

Answer 9

inducing or inhibiting liver enzymes has minimal effect on the high HER, but significantly affects proportion escaping extraction and significantly impacts F

Question 10

Bioavailability is determined by what two things

Answer 10

Absorption

Extent of First pass metabolism

Question 11

High HER drugs characteristics

Answer 11

results in variable bioavailability
determines route of admin
are affected by a) drug interactions b)liver disease